Belt grinding machine



G DEN HERDER BELT GRINDING MACHINE Aug. 23, 1966 Filed Feb, 17, 1964 Aug. 23,` 1966 G. DEN HERDER BELT GRINDING MACHINE 2 Sheets-$heet 2 Filed Feb. 17, 1964 Dn E D R E H N E D D A Dn E G INVENTOR.

AT TOR NE YS 3,267,619 BELT GRINDING MACHINE Gerald Den Herder, Tacoma, Wash., assignor to Square Wheel Co., Seattle, Wash., a corporation of Washington Filed Feb. 17, 1964, Ser. No. 345,147 8 Claims. (Cl. 51-148) This application is a continuation-.in-part of my copending application, Serial No. 284,506, filed May 31, 1963, and now Patent No. 3,187,471.

The present invention relates to belt grinding apparatus having provision for easy changing to various contact surfaces for grinding fiat surfaces or curved surfaces having a wide range of radii.

An important object of the invention is to provide a small, compact, and relatively inexpensive belt grinding machine whereby the operator can grind a variety of surfaces accurately to very close tolerance and in which the working area is easily accessible from all working angles.

The invention further aims to make provision for the grinding of relatively inaccessible work areas, as for example, the wells on the hub of a boat propeller between the propel-ler blades.

Still another important object is to provide such a belt grinding machine wherein provision is made for easy belt tracking and tension adjustments.

Other Imore particular objects and advantages of the invention, will, with the foregoing, appear and be understood in the course of the following description and claims, the invention consisting in the novel construction and in the adaptation and combination of parts hereinafter described and claimed.

In the accompanying drawings:

FIG. 1 is a side elevational view of the herein described belt grinding apparatus equipped with an optional contact wheel.

FIG. 2 `is a front elevational view of the machine of FIG. l.

FIG. 3 is a detail horizontal sectional vieu/.taken as indicated lby line 3 3 of FIG. l.

FIG. 4 is a vertical sectional View taken along the line 4 4 of FIG. 3.

FIG. 5 is a fragmentary longitudinal vertical sectional view `looking toward the inner face of the stationary side wall of the frame and with part of such wall broken away, showing the belt grinding apparatus equipped with an optional contact assembly.

FIG. 6 is a View taken the same as in FIG. 5 but with the contact assembly in another of its option-al positions; and

FIG. 7 is a detail fragmentary sectional view taken on line 7-7 olf FIG. 6.

The grinding apparatus of the present invention is mounted on a horizontal base 10 which is adapted to clamp over the edge of a work table. Upstanding from this base is a frame structure which includes a fixed vertical side plate 11 and a movable side plate 12 hinged along its lower edfge at 13 and held in a normally upright positi-on by a tie -bolt 14 which extends from the fixed side plate 11 and carries a wing nut 14a. A grinding shield 1S is pivoted at the top of the frame and an electric motor 16 is mounted at the rear of the base 10. The motor is controlled by a switch 17 convenient to the hand of the operator and drives a pulley 18 located between nited States atent C) Patented August 23, 1966 the side pl-ates at the rear thereof. A 'brake 20 operated by a lever 21, is arranged to work on lthe surface of the pulley to arrest its motion when desired.

Pivoted at 22 near the front off the fixed side plate 11 is a swing plate 23 which together with an arm 24 provide two sides of a parallel linkage. The arm 24 is pivoted at 25 to the side plate 11 in such a manner that the pivots 22 and Y25 collectively define a line parallel to the base :10. This line defines the third side of the parallel linkage and is complemented by a link taking the form of -a block 26 which fits within an offset portion 23a in the swing plate. A pivot pin 27 extends through this offset portion into the outer face of one end of the block 26 to form a pivot diagonally opposite the pivot 25 while the inner face of the block near its other end is cut back and receives a pivot pin 28 for the respective end of the ar-m 24. With this arrangement the block remains in a horizontal position during movement of the swing plate 23.

Spaced to the rear of the swing plate 23 is an arcuate ratchet 30 centered relative to the pivot 22. 'Ihe teeth 30a of the ratchet are directed outwardly away from the side plate 11 to selectively receive a pawl rod 31 which is offset at its inner end. This offset portion is circumferentially grooved to fit within the bottom of the boss for the pivot 22 and to receive in the groove a set screw 32 as shown in FIG. 7. By this arrangement the rod 31 can be swung outwardly into engagement with the inner face of the side plate 23 (full line position in FIG. 3) and its free end sprung outwardly slightly to clear the tips of the ratchet teeth 30a, and then swung inwardly to engage the rod with a selected tooth (broken line position in FIG. v3). At its outer end the rod is ybent :outwardly and threaded to receive ra knob 33 serving as a handle.

The offset portion 23a of the swing plate 23 has an arcuate slot 34 formed therein having the pivot 22 as its center. The purpose of this slot is to receive a threaded boss 35 into which is received an adjusting screw 36 which is tapered at its inner end and has a'knurled handle 37 at its outer end. The tapered portion 36a of the adjusting screw passes into an elongated slot 38 formed in the block 26 and bears against one edge of the head 40a of a dead shaft 40. This shaft projects through an elongated arcuate slot 41 in the side plate 11 to receive the bearing 43a for the hub of an idler pulley 43. The head 40a has convex arcuate vertical side faces and flats top and bottom which bear against the upper and lower Walls of the slot 38. A split pin 39 extends through these walls and through the head 40a to permit swinging movement of the shaft 40 in a horizontal plane. Such movement is resisted on the one hand by the tapered head 36a on the adjusting screw 36 and on the other -hand by a leaf spring 42 of general L configuration which is screwed to the inner face of the block and extends into the forward end of the slot 38.

With this arrangement backing off ofl the adjusting screw 36 permits the leaf spring 42 to swing the idler shaft forwardly in the horizontal plane and thereby skews the idler 43 out of a vertical plane which is parallel to the drive pulley 18. On the other hand, tightening of the adjusting screw 36, by the wedging action of its tapered inner end, forces the head of the shaft 40 against the leaf spring 42 thereby swinging the outer end ofthe shaft horizontally toward the rear of the machine. The purpose of this skewing of the idler shaft 43 is to adjust the tracking of the belt, denoted 44, such a practice being well known in the art. The action of the swing plate 23 provides vertical adjustment of the idler shaft 43 so as to vary the tension on the belt 44. In this regard, the rod 3l has sufficient spring action to give some spring loading of the idler shaft 4t?.

At the front of the machine there is located a clamp plate 46 which has a pair of horizontal slots d8 near its base receiving anchoring bolts 48a providing fore-and-aft adjustment of the clamp. An intermediate slot 419 is also p-rovided to receive the reach 53a of a rest :5S when work support is desired, the rest being shown in phantom in FIG. 1. At its upper end the clamp plate 46 projects forwardly beyond the side plate 11 and is horizontally and ventically slit at 46a-6b and laterally bored at 46c to provide a clamping jaw 50. rThis jaw is cinched by action of a set screw 51 which extends downwardly and has an Allen head for receiving a suitable tightening wrench.

One of the purposes of the clamp Sil is to selectively receive a dead shaft 52a on which a cog-tooth contact wheel 52 is journaled. This wheel is used when aggressive stock removal is desired. As an alternative to the contact wheel 52 there is provided a contact assembly denoted generally as 53. This assembly comp-rises a length of angle iron 54 providing a side plate Stia and a platen 5ft-b. In addition, intermediate the ends of the side plate 54a the contact assembly presents .a stub post 55 for reception in the clamp Si)v while at its opposite ends it provides dead shafts Saa-57a for contact wheels 5-5-57 which are journaled thereon. These contact wheels are preferably of different diameters thereby providing grinding heads accepta-ble to work of different radii.

The operation of the herein descpibed grinding apparatus is as follows. Assuming that a curved surface is to be ground, a backing head such for example as the contact wheel 52 is positioned in the clamp. in this regard, since the drive pulley l5, the upper idler 43, and the contact wheel all have their shafts cantilevering toward the side plate l2 a grinding belt can be easily installed merely by loosening the wing nut lila and swinging the slide plate 12 downwardly to expose the pulleys. Then, after installation of the belt the upper tensioning pulley is adjusted by manipulation of the rod 3l on the arcuate ratchet 3G. When this adjustment is completed the knob 37 is turned to adjust, by the screw 35, the tracking angle of the idler e3 so that the belt la travels properly over the contact wheel 52.

lf the grinding of a flat surface is contemplated, or if curved surfaces of varying radii are t-o be ground, then the contact assembly S3 may he employed. This unit is readily interchangeable with the contact wheel 52 merely by loosening the set screw Si of the clamp 5t?, removing the dead shaft 52a, and inserting the stub 55. The contact assembly 53 is usable in four positions. It may be used in the position of FIG. 5 wherein the grinding radius is determined by the size of the smaller idler pulley 57. On the other hand, it may be rotated 180 from this position to bring the larger idler pulley 56 into working position. The drive of this pulley then determines the grinding radius. Still further, the assembly 53 may be employed -in the position of FIG. 6 which brings .the platen 562-5 into its working position underlying the abrasive belt This gives a good backing when fiat work is to be accommodated. lf then, the assembly S3 is rotated 180 from its hat work position the area of the grinding belt i4 between the wheels 56-57 will be unsupported. Accordingly, a yoke contact of the belt with the work is provided so that any desired radius may be put on the work, such being determined in part by the pressure applied to the belt, since the latter deforms under the pressure. It will be noted that in all of the above described situations, the grinding area of the apparatus is projected forwardly beyond the frame to la readily accessible position,

Thus, by the present invention there is provided a relatively simple, inexpensive apparatus which nevertheless is highly efficient in its operation and which is versatile in fig-ete providing grinding surfaces adaptable to all of the commonly encountered grinding applications found in the average shop.

lt is thought that the invention will have been clearly understood from the foregoing detailed description. Changes in the details of construction will suggest themselves and may be resorted to without departing from Iche spirit of the invention, wherefore it is my intention that no limitations be implied and that the yhere-to annexed claims be given a scope fully commensurate with the broadest interpretation to which the employed language admits.

What l claim is:

l. in a belt grinding machine having a frame and a removable driven abrasive belt carried on parallel spaced shafts cantilevered from one side of said frame, a block adjacent said frame, swing means on said frame for swinging said block in a plane parallel to that occupied by said belt, said swing means comprising a parallel linkage having parallel spaced swing members pivoted at one end to said block and at their other end to said frame, positioning means for holding said block relative to said frame in selected positions of its swinging travel, a dead shaft cantilevered from said block toward said belt, and a tensioning idler for said belt journal-mounted on said dead shaft.

.2. The structure of claim 1 in which said positioning means comprises a ratchet plate mounted on said frame and having its teeth projecting away from the belt, and an elongated pawl for said ratchet carried by one of said swing members and movable toward and away from said ratchet teeth.

3. ln combination with the structure of claim it, adjusting means on said block for selectively skewing said dead shaft out of panallel relation relative to said parallel spaced shafts in a plane parallel to such shafts.

In a belt grinding machine having a frame and a removable driven abrasive belt carried on parallel spaced shafts carried by said frame, a block, swing means on said fra-me for swinging said block in a plane parallel to that occupied by said belt, positioning means for holding said block relative to said frame in selected positions of its swinging travel, .a tensioning idler for said belt carried by said block for rotation about an axis approximately parallel to said parallel spaced shafts, and adjusting means on said block for selectively skewing the axis of the idler out of parallel relation to said parallel spaced shafts.

5. ln a belt grinding machine having a frame and a driven abrasive belt, a tensioning idler for said belt jouirnal-mounted on a dead shaft, an elongated block extending in a generally horizontal position and having an elongated horizontal through slot receiving the head of said shaft, a generally vertical pin extending through said block and the head of said shaft whereby said shaft may have its outer end swung in a generally horizontal plane, spring means in said block resisting swinging of said shaft in one horizontal direction, adjusting means for selectively urgng said shaft to swing in the opposite direction in opposition to said spring means, means on said frame for swinging said block while holding the same in generally horizontal position, and positioning means for holding said block relative to said frame in selected positions of its swinging travel whereby the tension on said belt may tue varied.

6. ihe structure of claim 5 in which said means for swinging said block comprises a generally vertical parallel linkage having two of its opposite sides composed of a swing plate and a swing arm having their upper ends pivotally connected to said block and lower ends pivoted at points spaced apart the same distance that their opposite ends are pivotally connected to said block, said points defining a generally horizontal line which is par-allel to said blocks, and means for pivotally connecting said swing plate and arm at said points on said frame, said positioning means being arranged to selectively position said swing plate and thereby hold said block in selected positions.

7. The structure of claim 6 in which said positioning means comprises an arcuate ratchet plate secured to said frame and having the pivot point for said swing plate as its center; and an elongated pawl carried by said swing plate and movable toward and away from the vteeth of said ratchet plate.

8. The structure of claim 5 in which sa-id positioning means comprises a ratchet plate secured to said frame with its teeth projecting away from said belt, and an elongated pawl pivotally mounted on said swing plate for movement only toward and away from engagement with said ratchet teeth.

References Cited by the Examiner FOREIGN PATENTS 680,107 10/ 1952 Great Britain.

ROBERT C. RIORDON, Primary Examiner.

10 L. M. SWINGLE, Examiner.

L. S. SELMAN, Assistant Examiner. 

1. IN A BELT GRINDING MACHINE HAVING A FRAME AND A RE MOVABLE DRIVEN ABRASIVE BELT CARRIED ON PARALLEL SPACED SHAFTS CANTILEVERED FROM ONE SIDE OF SAID FRAME, A BLOCK ADJACENT SAID FRAME, SWING MEANS ON SAID FRAME FOR SWINGING SAID BLOCK IN A PLANE PARALLEL TO THAT OCCUPIED BY SAID BELT, AND SWING MEANS COMPRISING A PARALLEL LINKAGE HAVING PARALLEL SPACED SWING MEMBERS PIVOTED AT ONE END TO SAID BLOCK AND AT THEIR OTHER END TO SAID FRAME, POSITIONING MEANS FOR HOLDING SAID BLOCK RELATIVE TO SAID FRAME IN SELECTED POSITIONS OF ITS SWINGING TRAVEL, A DEAD SHAFT CANTILEVERED FROM SAID BLOCK TOWARD SAID BELT, AND A TENSIONING IDLER FOR SAID BELT JOURNAL-MOUNTED ON SAID DEAD SHAFT. 